Aspergillus Green Mold

Microscopic Characteristics Sporulating structure tall, unbranched, stalk-like, supporting at its apex a spherical head to which linearly arranged chains of single celled spores (conidia), measuring 3-5 microns, are attached. 

History, Use and/or Medical Implications Some species toxic. Aspergillus flaws, a yellow to yellowish green species, produces the deadly aflatoxins. A. Havus attacks cottonseed meals, peanuts and other seeds high in oil that have been stored in hot, damp environments. Of all the biologically 

Since A. flavus grows on practically all types of grain, this species is of serious concern to mushroom spawn producers. Careful handling of any molds, particulary those of the genus Aspergillus, should be a primary responsibility of all managers and workers in mushroom farms, Aflatoxins are not, however, taken up in the fruitbodies when contaminated spawn or cottonseed meal is used to supplement a compost. 

Aspergillus niger, the common black mold, has been cultured commercially for its ability to 

Comments This is a dangerous genus. Since one can encounters Aspergillus flavus, A. niger, A. fumigatus in the course of mushroom culture, precautionary steps should be undertaken to minimize exposure to these toxic contaminants. 

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Order 3.— Plectascales, the blue and green molds. Examples Aspergillus and Penicillium. 

Every day or so inspect the jars and check for the slightest sign of contamination. The most common are the green molds PenidiHum and, Aspergillus. If contamination is detected, sea the lid and remove the infected culture from the laboratory and growing facility. If ajar is suspected to be contaminated, mark it for future inspection. 

Plate 21 Aspergillus, the Green Mold, growing on malt agar media. 

Delayed action cytotoxins that inhibit the synthesis of nucleic acids. They are obtained from various molds/fungi (Aspergillus flavus, Aspergillus parasiticus). They are colorless to pale-yellow crystalline materials melting above 450°F. The "B" toxins fluoresce blue in the presence of UV light while the "G" toxins fluoresce green. They are only slightly soluble in water, but are soluble in methanol, acetone, and chloroform. Aqueous solutions are "probably stable" and "probably tolerant" to chlorine at purification concentrations. 

Aspergillus oryzee is a yellowish-green to brown mold which secretes diastase, a valuable digestive ferment, having the power of converting starch into sugar and dextrin. For centuries the Japanese have employed this species in the preparation of rice mash for... 

Molds are hlamentous microorganisms, that is, the cells stay attached to each other to form long hlaments. Many molds can form spores, which are generally different in colors, depending on the kind of mold. Species of Aspergillus often form black spores, while Penicillium is recognized by blue or green spores. Mold spores serve the purpose of reproduction, but they are not resistant to heat or chemicals. 

The problem with the simple TLC analysis of aflatoxins is that many natural products fluoresce blue or green under UV and many of these compounds have an Rp value close to, or even identical with, that of one of the four common aflatoxins (Figure 1). The early literature contains a number of false-positive reports of the presence of aflatoxins, and even their production by species of mold other than Aspergillus flavus, A. parasiticus, and A. nomius, so it is essential that a confirmatory test be carried out such as derivatization coupled with two-dimensional TLC. In the case of the aflatoxins, a useful confirmatory test is to derivatize as the hemiacetals with trifluoroacetic acid by superimposing 2 pi of a 50% solution of the reagent in chloroform onto the spot of both the unknown and a standard marker before chromatography. Aflatoxins Bi and Gi, but not B2 and G2, form hemiacetals that have the same fluorescence as the parent compound but run significantly more slowly... 

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